Tension device for band-saws.



P. T. MUDONOUGH. TENSION DEVICE FOR BAND SAWS.

' APPLICATION FILED 33.21, 1908. 928,21 1.

Patented July 13, 1909.

4 SHEETS-SHEET 1,.

F. T. MODONOUGH. V TENSION DEVIUE FOR BAND SAWS.

1 APPLIV[OATI0H TIL-ED PEB|21| 1908. I Patented 4 SHEETS-SHEET 2.

wi tmaow anemia ANDREW. a. GRAHAM (:0 Pnnvmmnoammus, WAEHINGTOM, n c.

4 SHEETB-SHEBT 3.

G Hozn mg I. T. MODONOUGH-' TENSION DEVICE FOR BAND SAWS.

APPLICATION FILED 33.21, 1908. 928,21 1. Patented July 13, 1909.

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F. T. MGDONOUGH.

TENSION DEVICE FOR BAND SAWS.

APPLICATION FILED 1 1212.21 190s.

, 928,21 1. Patented July 13,1909.

wi bmoow FRANCIS THOMAS MCDONOUGH, OF EAU CLAIRE, WISCONSIN.

TENSION DEVICE FOR BAND-SAWS.

Original application filed March 20, 1907, Serial No. 363,526.

/ Specification of Letters Patent.

Patented July 13, 1909.

Divided and. this application filed February 21., 1908.

Serial No. 417,112.

To all whom it may concern:

Be it known that l, FRANoIs TnoMAs Mo- DONOUGH, a citizen of the United States, residing at Eau Claire, in the county of Eau Claire and State of Wisconsin, have invented a new and useful Tension Device for Band- Saws, of which the following is a specification.

The present invention is a division of the application filed by me Mar. 20, 1907, Serial No. 363,526, for an improvement in horizontal band resawing machines, and relates to a tension device.

The object of the present invention is to improve the construction of tension devices, and to provide a simple and comparatively inexpensive one of great strength and durability, adapted to afford greater access to the various parts, and capable of enabling the adjustable band saw wheel with which the tension device is connected to be readily moved toward and from the other band saw wheel for accommodating band saws of different lengths.

A further object of the invention is to enable the tension device to be readily relieved of the weight, when it is desired to adjust the band saw wheel with which the tension device is connected.

With these and other objects in view, the invention consists in the construction and novel combination of parts hereinafter fully described, illustrated in the accompanying drawings, and pointed out in the claims hereto appended; it being understood that various changes in the form, proportion, size and minor details of construction, within the scope of the claims, may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention.

In the drawings :Figure 1 is a rear elevation of a horizontal band resawing machine, provided with a tension device, constructed in accordance with this invention. Fig. 2 is an end elevation of the same. Fig. 3 is an enlarged horizontal sectional view of a portion of the horizontal band resawing machine, illustrating the arrangement of the tension device. Fig. 4 is a longitudinal sectional view of the same, taken substantially on the line 44 of Fig. 3. Fig. 5 is an enlarged transverse sectional view, taken substantially on the line 55 of Fig. 4. Fig. 6 is an enlarged detail sectional view, taken horizontally of the tension device. Fig. 7 is upper and lower pivots or trunnions 16 and 17, set at an inclination and mounted in upper and lower bearings 18 and 19 of yokes 20 and 21. The yokes, which are slidable horizontally, are provided with round stems 29 and 30, mounted in cylindrical openings 31 of the slidable carriers 32 and 33, arran ed in parallelism and saddling dove tailed guides 34. The dove tailed guides 34, which are preferably integral with the base 1, are provided with horizontal u per faces and have downwardly and inward y inclined side edges. The slidable carriers are provided with dove-tail grooves, formed by downwardly and inwardly inclined flanges 35, depending from the sides of the carriers, as clearly illustrated in Fig. 5 of the drawings. The slidable carriers are preferably provided with interiorly arranged wear plates 86, adapted to be adjusted by screws 37 to take up the wear and prevent any lateral vibratory movement of the carriers. The dove-tailed guides 34 are provided with central longitudinal slots 38 in which are slidably mounted rack bars 39, secured by screws 40, or other suitable fastening devices to the lower faces of the slidable carriers at the median line thereof, and extending inwardly from the carriers and meshing with gears 41 of a shaft 42. The inner portions of the rack bars are located beneath the top of the base and are provided at their lower edges with teeth 43. The toothed portions of the rack bars being interposed between the gears 41 of the shaft 42 and the top of the base, as clearly illustrated in Fig. 4 of the drawings. The gears 41, which are formed integral with the shaft 42, consist of teeth out into the same. The base is provided with suitable bearings for the shaft 42, which is adapted to be rotated to slide the carriers inwardly and outwardly, and the outer or rear end of the shaft 42 is provided with a suitable hand Wheel 43 to enable such operation to be performed by hand, when the shaft is relieved of the pressure of the weight, as hereafter fully explained. The outer or rear end of the shaft 42 also carries a ratchet wheel 44, having an extended hub portion 45 projecting inwardly and receiving the inner end of a straining lever 46. The straining lever 46, which is provided with an eye or opening to fit the hub portion 45, carries a pawl or dog 47, mounted on a stud 48 and provided with an arm 49. The pivot 48 is supported at the outer end by a bearing or bracket 48, and the arm 49 is provided at its outer end with a slot 50. The slot 50 receives a headed stud or rojection 51 of a s'hort hand lever 52, angul arly bent adjacent to one end and provided at the other end with a suitable grip or handle 53.

The angularly bent end is fu rumed on the straining lever 46 by means of a suitable pivot 52 consisting of a screw mounted in a threaded perforation of the straining lever, but a stud or pin may be mounted on the straining lever to form a pivot for the lever 52. The headed stud or projection 51 is located at the angle or bend, and it is arranged within the slot 50, whereby when the hand lever is swung upward or downward, a corresponding movement will be imparted to the arm 49, and the pawl or dog will be swung into and out of engagement with the ratchet wheel. When the hand lever 52 is swung upwardly or outwardly, the stud head 51 is carried to the outer end of the slot 50, and the lever will support the pawl or dog out of engagement with the ratchet wheel 44. The ratchet wheel 44 is held against backward movement by a check or retaining pawl 54, when the pawl or dog is out of en gagement with it. The check pawl 54 is pivotally mounted on the base, and when the pawl or dog of the straining lever is thrown out of engagement with the ratchet wheel 44, the shaft- 42 may be turned by hand to move the adjustable band saw wheel 5 inwardly or outwardly.

The straining lever is provided. with a curved outer or bifurcated. portion 55, composed of two sides spaced apart to receive a weight-carrying lever 56. The weightcarrying lever is pivoted at its inner end 57 on the base 1, and it is provided at an inter mediate point with a transverse pin 58, pro jecting laterally from each side of the lever 56 and operating in a curved slot 59 of the sides of the curved portion of the lever. The slot 59 extends upwardly and inwardly from the outer portion of the lever 46, the curvature of the slot 59 being such that the said lever 46 is raised slightly when the lever is swung upward. The inner end wall 60 of the slot orbifurcation of the curved portion of the straining lever is inclined and is adapted to form a stop for limiting the upward and inward movement of the weightcarrying lever. When it is desired to ad just the band saw wheel 5 by hand through the hand wheel 43 the weight-carrying lever, which is provided with an adjustable weight 61, is swung upward from the position illustrated in full lines in Fig. 1 of the drawings to that illustrated in dotted lines in the said figure to relieve the straining lever of weight. The pawl 47 is then disengaged from the ratchet wheel by operating the hand lever 52. The tension device is then free to be adjusted through the hand wheel 43 The weight 61 is adjustably mounted on the lever 56, and is adapted to be moved toward and from the pivoted. end 57 to apply the desired pressure on the band saw. The weight-carrying lever is adapted to be easily swung upwardly and downwardly, and it will be readily apparent that the weight may be directly applied to the straining lever, if desired.

The shank 29 of the front yoke 21 of the adjustable wheel 5 is adjustable independently of the rear yoke to aline the bearings for adjusting the shafts of the band saw wheels in parallelism and also to set the adjustable band saw wheel at an angle for leading the band saw 011 the wheels 4 and 5. When the shaft of the band saw wheel 5 is set at a slight angle to the shaft of the band saw wheel 4, the band saw will be caused to move in a transverse direction on the rims of the band saw wheels. This will enable the band saw to be advanced or led on the wheels. For this purpose, the shank 29 of the yoke 20 is provided at its outer portion with screw threads 62, which are engaged by a rotary nut 63. The rotary nut 63, which is in the form of a bevel gear, meshes with a bevel pinion 64 of an operating shaft 65, journaled in suitable bearings of an arm 66, and provided at its outer end with a hand wheel 67. The arm 66 is preferably formed integral with the adjacent slidable carrier 32, and the shaft 65, which is arranged at an inclination, extends upwardly and forwardly. The gearing for adjusting the yoke 21 moves the slidable carrier 32 and the rotary nut 63, which bears against the outer end of the lat ter, when rotated, moves the yoke 21 outwardly or inwardly. ()nly a comparatively small amount of adjustment of the yokes is necessary to set the wheel 5 at the proper angle for leading the band saw on the band saw wheels and for alining the shafts of the band saw wheels when the band saw is in proper position.

If desired, cushions 68 of rubber, or other elastic material, may be arranged at the outer ends of the slidable carriers to cushion the yokes to tend to relieve the band saw wheels and the band saw of and vibration.

The parts of the tension device for straining the band saw and the mechanism for moving the adjustable band saw wheels inwardly and outwardly are readily accessible for repair when necessary.

Having thus fully described my invention. what I claim as new and desire to secure by Letters Patent, is

1. In a sawing machine, the combination with a band saw, and a band saw wheel, of a tension device including a ratchet wheel, a straining lever, a separate weight-carrying lever provided with means for engaging the straining lever to actuate the same, said weight-carrying lever being arranged to swing out of such engagement to relieve the straining lever of pressure of the weight, a pivoted pawl mounted on the straining lever and engaging the ratchet wheel and provided with a slot, and a hand lever having a projection operating in the slot of the pawl and arranged to hold the latter in and out of engagement with the ratchet wheel.

2. In a sawing machine, the combination with a band saw, and a band saw wheel, of a tension device embodying a ratchet wheel, a

,straining lever, a separate weight-carrying lever provided with means for engaging the straining lever to actuate the same, said weight-carrying lever being arranged to swing out of such engagement to relieve the straining lever of pressure of the weight, a pawl pivoted to the straining lever and having an arm provided with a slot, a hand lever also fulorumed on the straining lever and provided with a projection operating in the slot of the said arm, said hand lever being arranged to hold the pawl in and out of engagement with the ratchet wheel, and a check pawl for engaging the ratchet wheel.

3. In a sawing machine, the combination with a band saw, and a band saw wheel, of a tension device embodying a straining lever, and a separate weight-carrying lever provided with means for engaging the straining lever to actuate the same, said weight-carrying lever being arranged to swing out of such engagement to relieve the straining lever of the pressure of the weight.

4. In a sawing machine, the combination with a band saw, and a band saw wheel, of a tension device embodying a straining lever, and a separate weigliit-carrying lever provided with means for engaging the straining lever and arranged to swing out of such engagement to relieve the straining lever of the pressure of the weight, said straining lever being arranged to support the weight-carrying lever in its disengaged position.

5. In a sawing machine, the combination with a band saw, and a band saw wheel, of a tension device embodying a straining lever, a weight-carrying lever fulcrumed eccentrically with relation to the straining lever and adapted to engage the same and movable out of such engagement, and arcuate means for limiting the independent movement of the weight-carrying lever.

6. In a sawing machine, the combination with a band saw, and a band saw wheel, of a tension device embodying a straining lever having a bifurcation, a weight-carrying lever operating in the bifurcation and arranged to be supported by the inner wall thereof, and means for limiting the outward swing of the weight-carrying lever for subjecting the straining lever to the action of the weight.

7. In a sawing machine, the combination with a band saw, and a band saw wheel, of a tension device embodying a straining lever having a curved slotted portion, and a weight-carrying lever provided with means operating in the slot for limiting the swing of the weight-carrying lever.

8. In a sawing machine, the combination with a band saw wheel carrier, of a tension device embodying a shaft having a pinion, a rack bar connected with the carrier and meshing with the pinion, a ratchet wheel mounted on the shaft, a straining lever having means for engaging and disengaging the ratchet wheel, and a weight-carrying lever engaging the straining lever and arranged to swing out of such engagement to relieve the straining lever of the pressure of the weight.

9. In a sawing machine, the combination with a band saw wheel carrier, of a tension device embodying a shaft having a pinion, a rack bar connected with the carrier and meshing with the pinion, a ratchet wheel mounted on the shaft, a straining lever having means for engaging and disengaging the ratchet Wheel, a weight-carrying lever engaging the straining lever and arranged to swing out of such engagement to relieve the straining lever of the pressure of the Weight, and means for manually rotating the shaft when the straining lever is disconnected from the ratchet wheel.

10. In a sawing machine, the combination with a band saw, and a band saw wheel, of a tension device embodying a straining lever, and an independently pivoted weight-carrying lever having a limited movement independent of the straining lever, said weightcarrying lever when at the limit of its movement in one direction being arranged to hold the weight in an inert position to relieve the straining lever and engaging the same at the limit of its movement in the opposite direction to put the said straining lever under tension.

In testimony that I claim the foregoing as my own, I have hereto affixed my signature in the presence of two witnesses.

FRANCIS THOMAS MCDONOUGH.

Witnesses B. I'IOGAN, E. A. ARNOLD. 

